The position of each sheet or bound document output by printers and post print finishing devices often varies according to the output tolerances of the particular device. Where multiple documents are output into a stack in the output tray, the edges of the documents are seldom aligned with one another. It is often desirable and sometimes necessary to align the documents in the output stack. One common alignment technique moves each document in one direction until one edge abuts a mechanical stop in the output tray, typically the side of the tray. A similar alignment technique moves each document in two directions until two edges abut a mechanical stop, typically the back and side of the output tray. These techniques for edge alignment are commonly referred to as registration, or registering the document. The technique for two edge alignment is commonly referred to as corner registration because each document is moved toward the corner of the tray. The present invention was developed in an effort to improve on conventional techniques for corner registering documents output by printers and post print finishing devices.